The United States and South Korea on Tuesday agreed to forge closer cooperation to maintain a strong defense against North Korea's proposed launch of a new satellite-bearing rocket, which is seen as part of Pyongyang's preparation for a possible nuclear test.

U.S. Defense Secretary Leon Panetta and his South Korean counterpart Kim Kwan-jin spoke over telephone to discuss what both sides termed as "highly provocative" action, reports quoting the Defense Ministries of both the countries said.

A South Korean Defense Ministry statement did not disclose what action was envisaged by the two staunch allies, who fought the 1950-53 Korean War against the North.

"Both leaders would regard a missile launch by North Korea as a serious provocation and a violation of North Korea's international obligations and standing U.N. Security Council resolutions," said a Pentagon spokesman.

Meanwhile, South Korea's Yonhap news agency quoted Transportation Ministry as saying on Tuesday that it would provide up-to-date information on the planned rocket launch to better protect ships that could be hit by falling debris.

All 15 maritime traffic control centers will be put on high alert and be ready to issue vital navigation warnings to safeguard vessels operating off South Korea's western and south-western coasts, it said.

North Korea has already placed the new Kwangmyongsong-3 satellite on its launch pad in the north-western cost of Tongchang-ri, which it says will shoot up between April 12 and 16.

The plan has sparked widespread criticism, including from the United States, South Korea and the European Union, as it is seen as a disguised long-range ballistic missile test.

Japan has warned that it will shoot down the "earth observation satellite," if it violates Japanese air space.

But North Korea says the launch is meant for "peaceful purposes," and to mark the birth centenary of its founder- leader Kim Il-sung, which falls on April 15.